People who suffer migraines with aura are thought to be at a higher risk of
stroke

It had been a normal Sunday for Caroline Osborn. She’d been out for a walk, done a spot of gardening, made some lunch and was settling down to watch rugby on television, a game she’d adored ever since attending a particularly lively Varsity match at Twickenham. It was then that she realised something was very wrong.

“I just couldn’t work out what was going on,” says Caroline, now 48, of that day six years ago. “I just couldn’t understand the game or add up the score. Then I got a massive headache and thought I was going to be sick. I managed to make it to the bathroom and collapsed, before losing my vision completely on one side. Luckily my ex-husband was a first aider and said I was having a stroke.”

Her quick-thinking partner was right. Caroline, an accountant from Brightlingsea, had suffered a massive ischaemic stroke, in which the blood supply to the brain is blocked by a blood clot. It left her in hospital for three weeks and permanently unable to return to the work she loved. But why, at the age of 42, had she fallen victim? “I’d never smoked, I drank very little, I had low blood pressure, I was a healthy weight and I was a keen rambler – walking up to 14 miles a day,” she recalls.

The answer, doctors concluded, was likely to be the migraines with aura that she had suffered on a six‑monthly basis since the age of 16. Two new studies, released ahead of a major neurology conference in San Diego in March, have revealed that this most severe form of migraine can be a higher predictor for cardiovascular problems than the more traditional risk factors such as smoking or family history. The authors urge younger women as well as older to make their doctors aware if they suffer migraines, particularly when being prescribed the contraceptive Pill.

In the UK about eight million people – one in four women and one in 12 men – suffer from migraine, a throbbing pain at the front or on one side of the head. A migraine attack is a lot more than just a headache: some people also have symptoms such as nausea or sensitivity to light. And about 15 per cent suffer “migraine with aura” – visual disturbances and other sensory symptoms, such as flashing lights, numbness, tingling of the hands and face, blind spots, or smell distortion, which come at the beginning of a migraine attack. For Caroline, it was her vision that would go – once most frighteningly when she was driving back from work and found herself with tunnel vision: “I lost my side vision – I still don’t know how I managed to get home.”

Preventative drugs such as betablockers and amitriptyline (an anti-depressant) have shown some success, as has Botox, licensed by Nice (the National Institute for Health and Clinical Excellence) for use in preventing migraine, but they do not work for all sufferers and they can have side‑effects.

While previous research has found a link between migraine and stroke and coronary heart disease, one of the new studies – which followed 28,000 women older than 45, over 15 years, as part of the landmark US Women’s Health Study – reveals for the first time that migraine with aura is a stronger predictor for heart attacks and stroke than other well-recognised risk factors: obesity, diabetes, smoking and family history.

In this group of women in total, researchers found there were 2.4 heart attacks or strokes per 1,000 women per year. But this rose to 9.8 per 1,000 women per year for women with high blood pressure, followed by 7.9 for women with migraine with aura. This rate was greater than women with diabetes, who suffered 7.1 heart attacks or strokes per 1,000 women per year, or those with a family history of heart attacks (5.4), current smokers (5.4) or the seriously obese (5.3).

However, the authors stress that the risk is still very small. “The important message here,” says Dr Tobias Kurth, neurologist at the University of Bordeaux and lead author, “is if you have suffered from migraine with aura in the past – even if you no longer have migraines – it is worth discussing this with your doctor, particularly if you have other risk factors for stroke and heart attacks.”

Researchers are still uncertain if migraine causes the increased risk of stroke – or whether there is a common underlying factor linking migraine and cardiovascular disease, such as a weakness in the blood vessels, or genetic factors.

“That’s the million-dollar question,” says Dr Mark Weatherall, consultant neurologist and trustee of the Migraine Trust. “Since Victorian times we have debated whether migraine is a vascular problem or a brain problem and the pendulum has swung back and forward. I think we are going to end up settling in the middle.”

Migraines are currently thought to be linked to changes in chemicals in the brain, in particular low levels of serotonin. This can make blood vessels contract (thought to cause aura) and dilate (causing the headache).

Another factor that may have played a part is the contraception Caroline used in her twenties: the combined Pill, which contains the hormones oestrogen and progestogen and which is another risk factor for stroke. “No one suggested to me that that could be a problem – but maybe it would have been different if I’d been having [migraines] more regularly,” she recalls. But a second study released ahead of the conference warned that women who suffer from migraine with aura and take the combined Pill should make their doctors aware of their condition, so they can be prescribed the progestogen-only mini-Pill instead.

The study of 145,000 women, ranging in age from 18 to 70, who suffered from migraine found that women who suffered migraine from aura and who (at some time) took a combined hormonal contraceptive were more prone to blood clot complications such as deep vein thrombosis (DVT). For example, 7.6 per cent of women with migraine with aura who used a new generation combined Pill had DVT compared with 6.3 per cent of women with migraine without aura. Again, because the study looked at events over more than a decade, it is not yet clear whether the women suffered such complications when they were actually taking the Pill or afterwards.

“What’s fascinating here is that these studies really seem to clarify that there is an issue with the particular subtype migraine with aura,” says Dr Weatherall. “The increased risk is very, very small – but if you add migraine with aura together with smoking, high blood pressure, being overweight or taking the combined Pill, then that can be a problem. While you can’t do anything about having migraine with aura, you can make informed decisions about the other factors.”

For Caroline Osborn, the important thing is to raise awareness to prevent other women ending up in her situation. Putting her life back together was difficult – her father even had to teach her to tell the time again. With little support from the NHS and social services after leaving hospital, her marriage subsequently collapsed. Her daughter Annabel and son Guy were only 12 and nine at the time of her illness. “It has affected them, but I’ve done my best and they are now at university and sixth-form college,” she says proudly.

Caroline has been left with some weakness down her left side and she tires easily. “It’s difficult – before my stroke I could earn my living and I had worked hard to pass my [accountancy] exams. Now the future’s uncertain for me, and I have whole weeks when I can’t get out of the house.

“But I’m very determined – and I cope with the circumstances I have. And I consider myself lucky, to be brutally frank: one in three people don’t survive a stroke.”